A General, Activator-Free Palladium-Catalyzed Synthesis of Arylacetic and Benzoic Acids from Formic Acid
作者:Lin Wang、Helfried Neumann、Matthias Beller
DOI:10.1002/anie.201802384
日期:2018.6.4
carboxylative synthesis of arylacetic and benzoic acids using formic acid (HCOOH) as the CO surrogate was developed. In an improvement over previous work, CO is generated in situ without the need for any additional activators. Key to success was the use of a specific system consisting of palladium acetate and 1,2‐bis((tert‐butyl(2‐pyridinyl)phosphinyl)methyl)benzene. The generality of this method is demonstrated
Synthesis of Enantioenriched α-Deuterated α-Amino Acids Enabled by an Organophotocatalytic Radical Approach
作者:Peng Ji、Yueteng Zhang、Yue Dong、He Huang、Yongyi Wei、Wei Wang
DOI:10.1021/acs.orglett.0c00154
日期:2020.2.21
preparation of diverse, enantioenriched α-deuterated α-amino acids. Distinct from the well-established two-electron transformations, this radical-based strategy offers the unrivaled capacity of the convergent unification of readily accessible feedstock carboxylic acids and a chiral methyleneoxazolidinone fragment and the simultaneous highly diastereo-, chemo-, and regioselective incorporation of deuterium
Mechanism of Methyl Esterification of Carboxylic Acids by Trimethylsilyldiazomethane
作者:Erik Kühnel、David D. P. Laffan、Guy C. Lloyd-Jones、Teresa Martínez del Campo、Ian R. Shepperson、Jennifer L. Slaughter
DOI:10.1002/anie.200702131
日期:2007.9.17
Polarization IR spectra of the hydrogen bond in phenylacetic acid crystals: H/D isotopic effects
作者:Henryk T. Flakus、Michał Chełmecki
DOI:10.1016/s1386-1425(01)00642-4
日期:2002.7
This paper deals with experimental studies and with quantitative interpretation of the polarized IR crystalline spectra of phenylacetic acid and of its deuterium isotopomers d(2) and d(7). The spectra were measured in the v(O-H) and in the v(O-D) band frequency ranges at temperatures of 298 and 77 K. The intensity distribution in the bands was quantitatively reproduced on the basis of the strong-coupling model, when assuming that the isolated (COOH)(2) and (COOD)(2) cycles were the source of the spectral properties of the crystals. Such approach appeared to be sufficient for explaining most of the isotopic and the temperature effects in the spectra. A vibronic mechanism, promoting the symmetry forbidden transition in the IR for the totally symmetric proton stretching vibrations in centrosymmetric hydrogen bond dinners, was found to be of a considerably minor importance, when compared with analogous properties of arylcarboxylic acid crystals. The spectra of phenylacetic acid crystals, unlike the spectra of arylacetic acid crystals do not exhibit the so-called H/D long-range isotopic effects, depending on an influence of the aromatic ring hydrogen atoms on the v(O-H) band fine structure patterns. Also no Fermi resonance impact on the v(O-H) band shape was identified in the phenylacetic acid crystal spectra. These effects were ascribed to weakening of electronic couplings between the hydrogen bonds and the phenyl rings, due to the separation of these groups in phenylacetic acid molecules by methylene groups. (C) 2002 Published by Elsevier Science B.V.